The present invention relates to a vehicle hoist of the type including a base, an inclined column fixedly secured to the base and vehicle support means secured to a carriage which is displaceable along the column.
Vehicle hoists of the above type have long been known in the art and have found a broad acceptance in car repair workshops due to their relatively low price and also due to their relative rigidity and manoeuverability.
Prior art typical of the field to which the present invention pertains is represented by Canadian Pat. No. 946,371, (Johansson); U.S. Pat. No. 3,363,778 (Larsson); U.S. Pat. No. 3,402,828 (Vilter); and U.S. Pat. No. 3,647,183 (Rishovd).
Generally speaking, the drawback of known lift devices of this type is seen particularly in relatively complex configuration of the different elements of the hoist which make the work with them relatively hazardous. Some of the known devices have hydraulic lifting means which are deemed to be preferred for this type of equipment, combined with mechanical device designed to prevent the carriage from inadvertently dropping down on defect of the hydraulic device. The above Vilter patent is one example of such prior art. The device is relatively cumbersome to operate and may result in the operator eventually abandoning the use of the mechanical safety device (a chain in the case of the Vilter patent) thus increasing the danger of accidental sudden drop of the carriage of the lift.
It is a primary object of the present invention to provide a vehicle lift of the above type in which the safety of operation would be improved and which would produce as smooth surfaces of the individual components of the lift as possible, particularly as regards the column housing the lifting carriage.
In accordance with one aspect of the present invention, a vehicle hoist is provided of the type including a base disposed normally horizontally on the ground and having a first end portion and a second end portion; a column fixedly secured to the base and extending upwards therefrom at an inclination such that a bottom end of the column is secured to said base at a point relatively close to but spaced from said first end portion and a top end of said column is generally vertically above said first end portion; carriage means disposed in said column for movement therein in the direction from one of said ends of the column to the other; first hydraulic power means operatively associated with said carriage means for selectively moving same along the column on actuation of manual control means; vehicle support means secured to said carriage and protruding from same in a direction away from that face of said column which is turned away from said first end portion; mechanical lock means normally biased such as to prevent the movement of said carriage means in the direction from the top end to the bottom end of the column; manual lock release means independent of and distinct from said manual control means for actuating said lock means against its bias, the manual lock release means being of the type requiring a continuous manual force to maintain the lock means in released state; whereby an operator must use his both hands to initiate the descent of said carriage means and must maintain manual force on said lock release means throughout the descending of the carriage means.
Preferably, the lock release means is disposed at that face of said column which is turned away from the vehicle support means, thus making it necessary for an operator to stand out of reach of the supported vehicle if the hoist is to be lowered.
According to a further feature of the present invention, the column is a structure of channel shaped cross-sectional configuration comprising a generally solid bottom wall provided with a plurality of transverse locking protrusions; a pair of side walls extending along each side of the bottom wall, each side wall having a longitudinally inwardly turned flange forming guide means for guiding said carriage along the bottom wall, said carriage being provided with transverse locking bar means complementary with said locking protrusions, and spring means resiliently urging said locking bar means into engagement with said locking protrusions; said locking protrusions being each a generally triangular cross-sectional shape defined by a locking surface generally perpendicular to the bottom wall, and by a wedging surface extending from the free end portion of the locking surface downwards and merging with the bottom wall, whereby the movement of the carriage upwards results in automatic release of the locking bar means in a ratchet-like fashion. The column thus provides smooth surface which is less susceptible to becoming inadvertently obstructed by a tool or the like, thus increasing the safety of operation. Also, the column has a smooth exterior surface.
In accordance with a further feature of the present invention, the hoist comprises a lock release bar extending along said bottom wall and generally centrally thereof and arranged for pivotal movement about an axis perpendicular with the elongation of the bar; said lock release bar being disposed between the bottom wall and the locking bar means, whereby a displacement of a portion of the lock release bar away from the bottom wall displaces the locking bar means from engagement with the respective locking protrusion. This arrangement provides an extremely simple, yet effective lock release, resulting in relatively low production costs of the particular elements.
The smooth exterior surfaces of the column are further enhanced by a further feature of the present invention in accordance with which the bottom wall, the side walls and the flanges are solid walls integral with each other and completely enclosing.the carriage at its sides and at its face turned toward said first end portion of the base, leaving only a part of one face of the carriage exposed between said flanges.
In order to enhance manoeuverability of the supported vehicle, the hoist of the present invention may be arranged such that said vehicle support means is pivotally secured to said carriage means for pivotal movement about a transverse axis closely spaced from said carriage, said hoist further comprising second hydraulic power means operatively associated with said vehicle support means and with said carriage means for selectively adjusting said vehicle support means from a normally generally horizontal position to a tilted position whereby the vehicle supporting means slopes downwardly and towards the column at an angle of inclination of about 20.degree..
In order to increase the manoeuverability of the hoist, particularly when the hoist is to be displaced while not supporting a vehicle, the hoist further comprises ground engaging wheels secured to said base and operatively associated with wheel mounting means adapted to allow displacement of said wheels from an extended position at which the wheels support the base at a spacing above the ground, to a retracted position wherein the base rests on the ground; and wheel extending spring means urging the wheels into said extended position, by a spring force only slightly greater than the weight of said hoist, whereby the wheels are forced into the retracted position when a vehicle is supported by same.
Thus, on engagement with a vehicle to be supported, the base of the hoist rests safely on the ground of a workshop, while, with the vehicle not supported by the hoist, the ground wheels extend automatically to enable withdrawal of the lift or the like manoeuvering, without any additional operation being required.
Thus, on engagement with a vehicle to be supported, the base of the hoist rests safely on the ground of a workshop, while with the vehicle not supported by the hoist, the ground wheels extend automatically to enable withdrawal of the lift or the like manoeuvering, without any additional operation being required.